1. Field of the Invention
The present invention relates to a reclining device for a vehicle seat. In particular, the invention is directed to a dual reclining device so designed that a pair of reclining elements are respectively provided to the two lateral sides of vehicle seat, with a connecting rod being operatively connected between the two reclining elements, wherein an operation lever is provided to one of the two reclining elements, and, by rotating the operation lever, a rotation as well as a locking/unlocking operation are imparted to one reclining device from the lever, while being simultaneously imparted to another reclining element at the same time via that connecting rod, for the purpose of adjustably inclining a seat back of the seat.
2. Description of Prior Art
There have been known various dual reclining devices of this kind, including a dual reclining device disclosed in the U.S. Pat. No. 4,909,572 for instance.
A typical construction of the dual reclining device is such that a pair of first and second reclining elements, each having a locking mechanism therein, are provided to the respective two lateral sides of a vehicle seat frame, wherein, for instance, the first reclining element only includes one operation lever, and that a connecting rod is operatively connected between the first and second reclining elements in order that rotation or locking and unlocking operations of the operation lever are impaired via that connecting rod to both of the first and second reclining elements at the same time.
In this dual reclining device, each of the first and second reclining elements has an upper arm and a lower base arm (see the designations 20A, 20B, 21A, 21B in FIGS. 1 and 2 for instance) In other words, the two upper arms of dual reclining device are connected with the two lateral fame portions of a seat back frame, respectively; whereas the two lower base arms thereof are connected with a seat cushion or a seat slide device. Each upper arm is roatably connected with each lower base arm via one end of the connecting rod. Hence, the upper arm is rotatable about both two ends of connecting rod or a center of rotation between the upper arm and lower base arm. It follows that one end of the connecting rod is disposed in one rotation center between the upper and lower base arms associated with the first reclining element, whereas another end of the connecting rod is disposed in another rotation center between the upper and lower base arms associated with the second reclining element.
In this particular dual reclining device, a widely available typical mode of the foregoing connecting rod is a tubular connecting rod having a non-circular end of a rectangular cross-section, for instance, and a circular end of a circular cross-section. On the other hand, for instance, the first and second reclining elements in the dual reclining device are respectively provided with a shaft having a non-circular end portion of rectangular cross-section and a shaft having a circular end portion of circular cross-section. Therefore, after having assembled both first and second reclining elements with a seat cushion frame and a seat back frame, the rectangular shaft end portion of first reclining elements is inserted and welded in the corresponding rectangular end of connecting rod, and then, the circular shaft end portion of second reclining element is inserted and welded in the corresponding circular end of connecting rod, whereby both first and second reclining elements are operatively connected together by the connecting rod.
In this process of forming the dual reclining device, it is quite often the case that the shaft of the first reclining element is not coaxially aligned with the shaft of the second reclining element. In that case, both first and second reclining elements can hardly be rotated simultaneously by the operation lever, and, technically, it would be difficult to extend the connecting rod on a rectilinear line between the first and second reclining element shafts. That is, a dislocation or non-alignment occurs between a central axis of the first reclining element and a central axis of the second reclining element. Considering such structural error or non-alignment, it has been a normal practice that an inner bore of the circular end of the tubular connecting rod is formed to have an inner diameter slightly larger than the circular shaft end portion of the connecting rod. Thus, when inserting the shaft end portion of second reclining device into the bore of connecting rod circular end, a certain play space is given peripherally of that shaft end portion so as to absorb an amount of error or non-alignment between the central axis of first reclining element and the central axis of second reclining element. Thereafter, a welding is effected to firmly connect the second reclining element shaft end portion with the connecting rod. However, it is very troublesome and difficult for a worker to position the circular end portion of second reclining element shaft at a predetermined point within the bore of corresponding circular end portion of connecting rod and weld the former with the latter precisely, which inevitably requires a separate support member or special aid means for that welding purpose.
In view of the above-stated drawbacks, it is a primary purpose of the present invention to provide an improved dual reclining device which permits both two end portions of connecting rod to be easily welded to two shafts of dual reclining device, irrespective of axial non-alignment between those two shafts.
In order to achieve such purpose, in accordance with the present invention, there is basically provided a dual reclining device in combination with a seat framework of vehicle seat including a seat back fame, the dual reclining device comprising:
a first reclining means provided on one lateral side of the seat framework, the first reclining means having a shaft;
a second reclining means provided on another lateral side of the seat framework, the second reclining means having a shaft;
both of the first and second reclining means being adapted for adjustably inclining the seat back frame;
a tubular connecting rod including:
one end portion have a bore in which the shaft of the first reclining means is fixed; and
a pressed and bent end portion of xe2x80x9cLxe2x80x9d shape which has a pressed region extending a longitudinal direction thereof and a transverse flange portion extending by a right angle from the pressed region, said transverse flange portion having a hole formed therein, and
the tubular connecting rod being connected between the first and second reclining means in such a manner that the shaft of second reclining means is not only inserted through and welded to the hole of transverse flange portion associated with the pressed and bent end portion, but also welded to the pressed region of pressed and bent end portion.
Accordingly, a welding can easily be effected not only to a point between the hole of transverse flange portion and the shaft of the second reclining means, but also to a point between the pressed region and that particular second reclining means shat, so that the connecting rod is set in a position between the two shafts respectively of the first and second reclining means.
In one aspect of the invention, the pressed region may be of an arcuate cross-section having a concave inward surface, and one side of the shaft be disposed in the concave inward surface of the pressed region and welded thereto. And, a diameter of the hole of transverse flange portion is larger than an outer diameter of the shaft of second reclining means, thereby absorbing or compensating for longitudinal and radial errors (non-alignment) between those two shafts respectively of the first and second reclining means.
Other features and advantages of the present invention will become apparent from reading of the description hereinafter, with reference to the annexed drawings.